Heat oil in a pan over medium-high heat.
Once the oil is hot, add asafetida, cumin seeds, and fenugreek seeds, and let them crackle for 4-5 seconds. Add ginger, garlic, and green chilies and fry them for 20-30 seconds.
Add green tomatoes, coriander powder, turmeric powder, red chili powder, and salt to the pan and mix well.
Reduce the heat to low. Cover the pan with a lid and cook until tomatoes are cooked through (10-12 minutes). Stir a few times while cooking.
Add jaggery and cilantro and mix well. Serve hot.